1. Field of the Invention
This invention relates to a brake mechanism for a winch having particular application to a winch for controlling the unwinding play out of the winch cable with the cable under unwinding induced load tension.
2. Background of the Invention
The type of winch as particularly contemplated herein is a winch mounted to the front bumper of a vehicle, specifically, a vehicle that has four-wheel drive and is driven on off road terrain. The winch includes a rotatable drum, a cable wound onto and off of the drum, and a motor and brake mechanism that controls the drum rotation.
Such a winch will be used to pull the vehicle up steep hills through mud and snow and for lowering the vehicle down steep slopes. Lowering a vehicle down a steep slope, in particular, creates a braking problem for the winch to which the present invention is directed.
A heavy weight or force pulls against the cable and urges unwinding of the cable from the drum. The drum can be locked against rotation to prevent unwinding quite satisfactorily with a number of brake designs. However, if the cable is to be controllably played off the winch, e.g., when lowering a vehicle down a slope, the braking action is that of controllably resisting or slowing the drum rotation in order to maintain control over the play out. In brake systems that are known, the application of such controlled resistive (as differentiated from preventive) braking action generates excessive heat, creates rapid wear, and results in early brake failure.